She has always been difficult, critical, tells lies that cause trouble, is sweetness and light where it suits her and really nasty when she wants to be. It grieves us to hear her playing these games the family know so well with her lovely nursing home staff, with high-handed verbal abuse and complaining complaining complaining that for "what she is paying, your wages you know" she isn't getting the service she expects. Some of the staff just shrug it off and try to deflect her (assuming its dementia), others say "you know exactly what you are doing and it's not nice" and come to dislike her (who can blame them). Other residents don't want to know her, she never joins in and treats people with disdain. Visits can be excruciating. If we remonstrate we just get told so we are the enemy too. If we say calming things and try to deflect, we feel we are not supporting the staff who are being abused. I'd be pleased to hear from anyone who has been in the same situation. Maybe kind words and thanks to the staff and cakes for teabreak are all we can do!
I'm sorry you have such a hateful mom, but that is on her not you. When she starts showing her ass when you visit, you just get up and walk out the door and tell her that you will come back another day when she is in a better mood. And you keep doing that over and over, until perhaps she gets it.
And if she doesn't it just means that you don't have to spend as much time with her as you probably have in the past.
So at least it's a win win for you.
If she's so unpleasant during phone calls and visits, then she doesn't deserve the time you take to do so, so stop visiting and accepting her calls or calling her if she acts like a baby.
If she's always been this way, she won't change now. So you've pretty much done all you can. I'd avoid her as much as possible, she sounds like an energy vampire.
Get mom to see a geriatric psychiatrist. She might benefit from counselling and/or medication.
We cannot be too kind to the staff. Their job is difficult in many aspects, plus they are on their feet walking most all day on an 8 hour shift. I gave a substantial gift card (Trader Joes) during the holidays. I was encouraged NOT to give money. In this situation, I wouldn't wait for a holiday. . . .
I'd bring pastries ... healthy snacks ... whatever ... a pizza for the staff.
Many caregivers or CNAs or aides in a facility cannot find other employment and have to do this work. Some are really good at it and their heart is in the right place. Others do it because they have to and don't care nor have the training or incentive to do anymore more than what is absolutely required ... and then at times they do not do the minimum.
Still. Developing good relationships with the staff, managers, and administrator is good - and can only help you - to help [the] your mother.
Bottom line: ask the medical staff for a recommendation. My own mom was always sweet and her behaviors declined to paranoia and fears/anxiety. The doc prescribed Olanzapine/Zyprexa. 10 mg to start since she was really over the top and then 5 mg. The positive is wonderful and when we tried to wean her off per her doctor (just to see if it was helping) she went back to mean, paranoid, anxious. We will never run out of these meds. The contraindications on the box are sobering, but I researched and read the papers of research and it is worth it for my mom since she is never going to get better and her terrors are abated with that little pill.
Unless you know the staff can make bad life threatening decisions, in which case, you need to move your Mom out of the facility.
...and just to be fair, if the story your Mom is telling is plausible, side with the staff ("Oh I'm sure there is a reason for that"), then start asking probing questions to your Mom to see if the story really is the whole story. If there is enough evidence to wonder, ask the staff for their version.
Just in case something really happens to your Mom, you don't want to completely shut her down. You do want to know if the facility is not performing up to your expectations, and your Mom is the person who would alert you.
Funny story: My Mom is in MC. For successive days, my Mom said that the staff did not give her a bath. Her hair looked like it had not gotten washed and her odor was "different." so the story was plausible. When I talked to the staff, they said that my Mom was refusing to bathe, saying that she didn't need it or thinking she had already taken one. I went back to my Mom and I said, "I heard you are refusing to take a bath." She said "they try to give me a bath 2 times in the same day and I tell them I don't need it." I told my Mom, "If they ask you to take a bath, you take that bath. I don't care whether you thought you already had one or not, just take the damn bath." She argued, I repeated myself. That night, when the caregiver came to give her a bath, she said "I know I already had a bath today. But, I better take the second bath or my daughter is going to be mad at me." We all got a good laugh. Success!
It sounds as though you have let your mother get away with this for far too long. But it's never too late to change.